Introduction
This Information Guide has been prepared by Con Edison (the Company) for customers
who are planning to install high tension substations. It provides a high-level, non-technical
introduction to the sequence of events involved in the construction of a high-tension
substation. Included are a high level schedule showing how major Customer and Con
Edison activities are sequenced and key points of information to assist our customers in the
development of their design and construction schedule.
This information guide is a companion to Con Edison’s Company specification EO-2022
“General Specification for High Tension service” which provides detailed technical
requirements.. This document is not intended as a design specification or an instruction
manual.
This document is for informational purposes only and Consolidated Edison Company of
New York shall not be held liable for indirect, special, incidental, punitive or consequential
damages of any kind including loss of profits, arising under or in connection with the use of
this Information Guide.
Description of High Tension Service
Con Edison provides service to high tension service Customers at a nominal voltage of 4kV,
13kV, 27kV or 33kV depending on location. To achieve this, the Company extends 4kV,
13kV, 27kV or 33kV feeders to a manhole at the Customer property line1 (or to a pole at the
Customer property line).
The Company owns and maintains its feeders up to the property line manhole and the
Customer will design, install, own and operate all equipment from the property line
termination point (manhole or splice chamber), including cables, circuit breakers,
transformers, and associated equipment (see figure 1). While the Customer owns the
substation, Con Edison evaluates the design and construction of the substation to ensure
that they will not have an adverse impact on the electric distribution system. As will be
shown later, Con Edison’s contribution to the project is primarily the performance of design
reviews and extension of its feeders to the customer premises.
1
The Company works with the Customer to select a convenient position for the property
line manhole to minimize the amount of street construction needed to extend the primary
feeder to the customer. Where the Customer prefers another location, they are usually
required to pay the difference in cost.
2
Figure 1 - Diagram of a Typical 4 Feeder High Tension Service
Communication between the Customer and Con Edison
Several departments within the Company will be involved in the High Tension project.
Some departments will be assessing the Customer’s design while others will be making
system changes to provide service. It is important that these groups are aware of the
Customer’s schedule and that the Customer is made aware of certain scheduling constraints.
For example, the Company does not typically perform work in the summer that requires an
outage on a feeder, as this is the period of peak electricity demand. The customer and
Company need to work together to ensure that tasks are scheduled, and completed, in a time
windows that minimize delays.
The Company will appoint a Customer Project Manager (CPM) who will act as the liaison
between the Customer and the Company. The CPM will ensure that the requirements of
each department are clearly communicated to the Customer and that the Customer’s
questions are directed to the appropriate internal department that can provide the answer.
2
Depending on load being served, between three and six feeders may be required.
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While the Customer may delegate the day to day management of the project to a consultant,
we encourage the Customer to periodically meet with the CPM to discuss the progress of the
project.
Figure 2- Typical Interactions between a customer and Con Edison
The Process
There are a number key milestones involved in a high tension project. The Customer’s
consultant should include these in the project timeline and the schedule should be updated
after each milestone has been reached.
Submission of Load letter to Con Edison
Preliminary Design Review
Kickoff Meeting
Receipt of Signed Con Edison HT specification (EO-2022)
Design Review
Complete Customer Conduit and Manhole Installation
Manufacturers’ Design Package Review
Final Design Review
Customer’s Electrical Equipment Installed
Con Edison Cables Installed
Pre-Operational Testing Completed
Metering/Energization
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Experience shows that the duration of a High Tension project is largely determined by the
pace of the design and construction of Customer facilities. Con Edison’s construction
activities will be coordinated to accommodate the customer’s schedule.
Figure 3 - Major HT Project Milestones
As you review the high-level schedule outlined in figure 3, keep in mind that the design is
not typically fully completed before construction starts. Construction begins once design of
major items is completed and detailed items are defined as the project progresses.
The duration of a High Tension project varies based on the complexity of the project, based
on factors such as number of feeders, green field construction vs. modification of an existing
facility. The timeline shown in figure 3 indicate the recommended sequence of major
milestones that have a Con Edison involvement. It is recommended that the Customer
include these milestones in their project plan that is submitted to Con Edison
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
Submit load letter to Con Edison
The initial service request (load letter) is typically delivered to the Customer Project
Manager (CPM) indicating the customer’s desire to obtain service at a certain
location. The service request will include a breakdown of the individual loads at the
service location. After internal engineering review, the CPM will provide a service
ruling indicating the service voltage, the number of feeders, the preferred point of
entry, etc. The Customer will use this information to develop the Customer’s
preliminary one-line diagram.

Preliminary Design Review
Once the customer has developed a one-line diagram, it is recommended that they
send it to Con Edison for a preliminary review.

Kickoff Meeting [Approximately 1 month after the initial inquiry]
After completing an initial review of the Customer’s One-Line diagram, the CPM
will schedule a meeting between Con Edison’s engineering group and the customer’s
engineering staff to discuss Con Edison’s high tension service requirements and any
site specific issues. During the course of this meeting, the Customer’s project
schedule and expected completion date will be discussed with respect to how the
Company-related portions of the project can be optimally sequenced. At this
meeting, the customer is expected to present a signed copy of the Company’s
specification EO-2022, which commits the Customer to meet the Company’s
standards.

Design Reviews [ Dependent on customer progress]
The Customer will be required to develop their substation design to meet the
Company’s interconnection requirements as identified by the preliminary One-Line, the
site specific design specification and associated Company’s general high tension
specification EO-2022. The Customer should submit their design documents when the
design is approximately 30% complete and again when the design is approximately 60%
complete. Experience has shown that such periodic review ensures that the Customer is
incorporating the necessary requirements and greatly reduces the need for changes and
the consequential delays in the project]
The first design submittal for review is at approximately 30% completion of the
substation design. At this stage we expect to see general equipment layout, cable
routing, etc. At the end of this review construction of switchgear rooms, ducts
and associated work will typically proceed, and major items such as switchgear
and transformers are ordered. This submittal shall at a minimum include the
following drawings:
AC One-Line Diagram
AC Three-Line Diagram
Substation Floor Plan (including room layouts)
Substation primary conduit plans and arrangements
Substation Grounding Plan and associated calculations
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Primary Switchgear Arrangements (Both Service and Utilization Voltage)
Transformer Vault Design
AC and DC Circuit Breaker control Schematics (Both Service and Utilization Voltage)
DC Control Battery One-Line diagram detailing the battery and charger types, distribution
panels, transfer switches, relaying and alarms, and associated calculations
Site Plan Showing Incoming Service Duct Arrangements and P/L MHs
Emergency generator details and arrangements (if applicable).
The Company shall issue comments subsequent to this review. The Customer should
meet with the Company’s engineering forces to discuss the design. The Customer will
be expected to address the comments issued by modifying these drawings as
appropriate and re-submitting these revised drawings for Company review and
acceptance.
The second design submittal, at approximately 60% completion and will add detail to
the items submitted in the 30% review. At this stage we expect to see protection
calculations, vendor drawings of major equipment already ordered (but not yet
delivered), cable terminations etc. This submittal will include the following:

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Bill of Materials - including all relays, voltage & current transformers (showing ratios
and connections), fuses, and interrupting & grounding devices
A relay coordination study and proposed protective relay settings
Termination Compartment equipment showing the arrangement of the cable
terminations, neon indicators and ground studs
Metering compartment equipment showing the physical layout & clearances, barriers,
and phasing facilities
Bus, Cables & Terminations (manufacturer's specifications)
Ground & Test Devices or Ground Switches - manufacturer, detailed description of
operation, equipment drawings, specifications, and interlocks
Vendor drawings and specifications
Emergency Generator - interlocking procedures, load to be supplied, and testing
schedule
The Customer shall subsequently submit the manufacturer’s design drawings for the
following equipment:
High Tension Switchgear (both Service and Utilization voltage)
Ground and Test Device arrangement drawings
Service/Isolation Transformer nameplate and arrangement drawings
Remote Control Monitoring Panel drawings
The customer’s Bill of Materials
Prior to final inspection and testing, the Customer shall submit final design documents
for review.

Pre Operational Testing [4-8 weeks]
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This includes such activities as relay testing, switchgear inspection and operational
tests, cable tests, completing meter installations, etc.

Feeder Energization
Customer Documentation - Prior to energization the Customer shall resubmit to
Energy Services their final submittal package corrected and marked final and stamped
by a Professional Engineer for Company record.

Outage Scheduling [1 week per feeder]
Once all testing is completed and the required documentation is in place, the CPM
will schedule the outages and initiate the splicing of the customer’s cable to
Company cable in the customer property line manhole. This is not typically done
during the summer as this is the period of peak electricity demand. The project
schedule should ensure that this point is arrived at outside summer months.
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Key Points of Information

The city of New York places an embargo on non-emergency street excavations
during the winter holiday period to minimize traffic disruptions. Company does not
typically perform non-emergency work on primary feeders between May 15 and
September 15. Customer property line manholes need to be completed before the
ducts can be built for the extension of primary feeders to the customer. The
customer should ensure construction of property line manholes are completed in
time to allow Company to build the necessary ducts before the embargo periods.

Experience has shown that High Tension projects typically take one to three years or
more to be completed, depending on the complexity of the Customer’s design. Early
submission and close coordination are critical to ensure the Customer’s desired
service date is met.
Reference
1. EO-2022 “General Specification for High Tension Service”.
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